Conventional inflatable protective devices (such as airbags or protective inflatable cushions) are oftentimes formed from a plurality of fabric panels sewn together to form the cushion. A throat or gas passage may be formed in the airbag for passage of inflation gas therethrough, from an associated inflator (for example, a gas generating system). The airbag/cushion may also be secured to the inflator along the throat to provide a gas-tight seal between the airbag/cushion and the inflator. The throat or gas passage may be defined by edges or other portions of the panels as the panels are sewn together.
The interior surfaces of the airbag or cushion may be coated with silicone to help protect against heat damage from hot gases and other by-products resulting from combustion of gas generant materials in the associated inflator. Although effective, the application of the protective silicone layer to the entire interior surface of the airbag or cushion is expensive. Furthermore, the weight and packaging size of the airbag or cushion is increased due to the weight of the inner silicone layer.
Inflators may also incorporate a metallic diffuser positioned so as to be in fluid communication with the gases exiting from the gas generator. Also, a metallic filter may be employed within the gas generator to function not only as a filter, but also as a heat sink. This may or may not be used in conjunction with the silicone coating on the airbag inner wall. By diffusing the gases, the impact of heat and other gas generant by-products such as hot gas and solids, for example, is distributed about the inner wall of the airbag. As such, the risk of damage to the airbag cushion because of a concentrated flow of heat, hot solids, and hot gases during actuation of the vehicle occupant protection system, is mitigated or eliminated. However, diffusers and filters add weight, complexity and cost to the inflator design.
Thus, it is desirable to minimize the weight and packaging size of the airbag, while still accommodating the protective concerns relative to the hot gas generating products as defined above. It is also desirable to simplify the design and reduce the cost of an associated inflator by eliminating the need for metallic diffusers and metallic filters, while still addressing the concerns described above.